(Invited) Electrochemical Tuning Sensing and Catalytic Performance of Catalytic Materials -from Nanoscale to Atomic Scale

Abstract

In this talk, we will introduce two facile methods for the preparation of a nanoporous Ag foam and a promising electrocatalyst for the oxygen reduction reaction (ORR). Ag has a high electrical and thermal conductivity, low cost, and is relatively abundant in the earth compared to other Pt-group metals. Unlike Pt-related noble metals, the poor hydrogen evolution reaction (HER) activity of Ag in acidic environments makes it rarely considered as a potential HER electrocatalyst. We demonstrate a spongy-like highly nanoporous Ag foam obtained using a simple Ag surface treatment through the repetitively electrochemical anodic formation of AgBr/cathodic reduction back to Ag exhibited Pt-like high HER activities. Bimetallic Pt-Ni with Pt on the outermost layer and an innermost layer enriched in Ni, referred to as (Pt3Ni(Pt-skin), is a promising configuration of electrocatalyst for the ORR in fuel cells. We prepare a core (Pd)/shell (Pt3Ni(Pt-skin)) catalyst (Pt3Ni(Pt-skin)/Pd/C) from Zn underpotential deposition (UPD) on a Ni UPD modified Pd/C catalyst, facilitating Pt atomic layer-by-layer growth on the Ni surface through the galvanic replacement process. The Pt3Ni(Pt-skin) thin layer with ultra-low Pt loading presents not only a breakthrough in Pt specific activity and Pt mass activity, both of which were superior to state-of-the-art Pt-Ni catalysts, but also in high durability owing to the perfect Pt3Ni(Pt-skin) construction